U.S. patent application number 16/075196 was filed with the patent office on 2019-02-07 for air-conditioning apparatus.
The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Daisuke ABE, Jun SOMEYA.
Application Number | 20190041070 16/075196 |
Document ID | / |
Family ID | 60000295 |
Filed Date | 2019-02-07 |
![](/patent/app/20190041070/US20190041070A1-20190207-D00000.png)
![](/patent/app/20190041070/US20190041070A1-20190207-D00001.png)
![](/patent/app/20190041070/US20190041070A1-20190207-D00002.png)
![](/patent/app/20190041070/US20190041070A1-20190207-D00003.png)
![](/patent/app/20190041070/US20190041070A1-20190207-D00004.png)
United States Patent
Application |
20190041070 |
Kind Code |
A1 |
ABE; Daisuke ; et
al. |
February 7, 2019 |
AIR-CONDITIONING APPARATUS
Abstract
An air-conditioning apparatus includes a refrigerant circuit in
which a compressor, a first heat exchanger, an expansion unit, a
second heat exchanger, and a first cooling unit having a
refrigerant path are connected to each other by a pipe and through
which refrigerant flows, a controller configured to control
operation of the compressor and having a heat-generating element, a
heat transfer element having a proximal end connected to the
heat-generating element and a distal end connected to the first
cooling unit, and conveying heat generated by the heat-generating
element, and a second cooling unit connected between the proximal
end and the distal end of the heat transfer element and cooling the
heat transfer element, and the first cooling unit cools the heat
transfer element using the refrigerant.
Inventors: |
ABE; Daisuke; (Tokyo,
JP) ; SOMEYA; Jun; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
60000295 |
Appl. No.: |
16/075196 |
Filed: |
April 7, 2016 |
PCT Filed: |
April 7, 2016 |
PCT NO: |
PCT/JP2016/061360 |
371 Date: |
August 3, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24F 1/24 20130101; F25B
31/006 20130101; F24F 1/22 20130101 |
International
Class: |
F24F 1/24 20060101
F24F001/24; F25B 31/00 20060101 F25B031/00; F24F 1/22 20060101
F24F001/22 |
Claims
1. An air-conditioning apparatus, comprising: a refrigerant circuit
in which a compressor, a first heat exchanger, an expansion unit, a
second heat exchanger, and a first cooling unit having a
refrigerant path are connected to each other by a pipe and through
which refrigerant flows; a controller configured to control
operation of the compressor and having a heat-generating element; a
heat transfer element having a proximal end connected to the
heat-generating element and a distal end connected to the first
cooling unit, and conveying heat generated by the heat-generating
element; and a second cooling unit connected between the proximal
end and the distal end of the heat transfer element and cooling the
heat transfer element, the first cooling unit cooling the heat
transfer element using the refrigerant.
2. The air-conditioning apparatus of claim 1, wherein the heat
transfer element comprises a tubular part having a hollow portion
in which a working fluid is sealed, and the distal end is located
above the proximal end.
3. The air-conditioning apparatus of claim 1, further comprising a
heat insulating material provided to the first cooling unit and
insulating heat of the first cooling unit.
4. The air-conditioning apparatus of claim 1, wherein the first
cooling unit is provided at a suction side of the compressor.
5. The air-conditioning apparatus of claim 1, further comprising: a
bypass circuit connecting a suction side of the compressor and a
portion between the first heat exchanger and the expansion unit; a
first refrigerant flow rate adjustment unit and a second
refrigerant flow rate adjustment unit provided on the bypass
circuit and each adjusting a flow rate of the refrigerant flowing
through the bypass circuit; and a bypass temperature sensor
measuring a temperature of the refrigerant flowing through the
bypass circuit, wherein the first cooling unit is provided between
the first refrigerant flow rate adjustment unit and the second
refrigerant flow rate adjustment unit, and the controller
configured to adjust the first refrigerant flow rate adjustment
unit and the second refrigerant flow rate adjustment unit in such a
manner that the temperature measured by the bypass temperature
sensor is between a bypass temperature upper limit threshold and a
bypass temperature lower limit threshold.
6. The air-conditioning apparatus of claim 1, wherein the second
cooling unit comprises a heat sink.
7. The air-conditioning apparatus of claim 1, wherein the second
cooling unit comprises a Peltier element.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a U.S. national stage application of
International Application No. PCT/JP2016/061360, filed on Apr. 7,
2016, the contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to an air-conditioning
apparatus that cools a heat-generating element provided in a
controller.
BACKGROUND
[0003] A board, an electrical component, and other components for
controlling operation of a conventional air-conditioning apparatus
are housed in an electric component box and provided in an outdoor
unit. By being housed in the electric component box, the board, the
electrical component, and other components are inhibited from being
exposed to rainwater or other material entering the outdoor unit
through an air inlet, an air outlet, and other part provided in the
outdoor unit. The electrical component that is a heat-generating
element that generates a large amount of heat such as a power
module is cooled to inhibit thermal destruction. An example of a
system for cooling the heat-generating element is an air cooling
system. In the air cooling system, for example, a large-sized heat
sink or other similar device is attached to the heat-generating
element, and thus an amount of heat rejected from the electrical
component is ensured. The heat sink is installed in an air passage
formed between the air inlet and the air outlet. The heat sink is
cooled by air flowing through the air passage, and the cooled heat
sink cools the electrical component. In the air cooling system,
when an amount of heat generated is increased, the heat sink needs
to be increased in size. Thus, the amount of metallic material to
be used and required for producing the heat sink is increased, so
that the production cost for the air-conditioning apparatus is
increased.
[0004] Patent Literature 1 discloses an air-conditioning apparatus
that employs a refrigerant cooling system as well as an air cooling
system as a system for cooling a heat-generating element. In Patent
Literature 1, a refrigerant pipe of a refrigerant circuit and a
power board housed in an electrical component box are joined to
each other with a refrigerant jacket interposed between the
refrigerant pipe and the power board, and the temperature of
refrigerant flowing through the refrigerant pipe is controlled to
be lower than the temperature of the power board. Then, heat
generated by the power board is rejected to the refrigerant, and
thus the power board is cooled. As described, Patent Literature 1
is intended to inhibit the temperature of the power board from
rising.
PATENT LITERATURE
[0005] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2011-99577
[0006] However, in the air-conditioning apparatus disclosed in
Patent Literature 1, as heat generated by the heat-generating
element is rejected to the refrigerant, the refrigerant is heated.
Thus, for example, during cooling operation, cooling capacity for
cooling an air-conditioned space is decreased. Consequently, the
operating efficiency of the air-conditioning apparatus
decreases.
SUMMARY
[0007] The present invention has been made to solve the
above-described problem, and provides an air-conditioning apparatus
that rejects heat generated by a heat-generating element, while
inhibiting a decrease in operating efficiency.
[0008] An air-conditioning apparatus according to an embodiment of
the present invention includes a refrigerant circuit in which a
compressor, a first heat exchanger, an expansion unit, a second
heat exchanger, and a first cooling unit having a refrigerant path
are connected to each other by a pipe and through which refrigerant
flows, a controller configured to control operation of the
compressor and having a heat-generating element, a heat transfer
element having a proximal end connected to the heat-generating
element and a distal end connected to the first cooling unit, and
conveying heat generated by the heat-generating element, and a
second cooling unit connected between the proximal end and the
distal end of the heat transfer element and cooling the heat
transfer element, and the first cooling unit cools the heat
transfer element using the refrigerant.
[0009] According to an embodiment of the present invention, the
heat transfer element that conveys the heat generated by the
heat-generating element is cooled by the second cooling unit
earlier than by the first cooling unit cooling heat using the
refrigerant. Thus, a load on the first cooling unit for cooling the
heat-generating element is reduced. Consequently, the
air-conditioning apparatus is capable of rejecting heat generated
by the heat-generating element while inhibiting a decrease in
operating efficiency.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a circuit diagram showing an air-conditioning
apparatus 1 according to Embodiment 1 of the present invention.
[0011] FIG. 2 is a front cross-sectional view showing an outdoor
unit 2 in Embodiment 1 of the present invention.
[0012] FIG. 3 is a top view showing the outdoor unit 2 in
Embodiment 1 of the present invention.
[0013] FIG. 4 is a side cross-sectional view showing the outdoor
unit 2 in Embodiment 1 of the present invention.
[0014] FIG. 5 is a schematic diagram showing a heat transfer
element 20 in Embodiment 1 of the present invention.
[0015] FIG. 6 is a schematic diagram showing movement of heat in
the heat transfer element 20 in Embodiment 1 of the present
invention.
[0016] FIG. 7 is another schematic diagram showing movement of heat
in the heat transfer element 20 in Embodiment 1 of the present
invention.
[0017] FIG. 8 is a circuit diagram showing an air-conditioning
apparatus 100 according to Embodiment 2 of the present
invention.
DETAILED DESCRIPTION
Embodiment 1
[0018] Hereinafter, an air-conditioning apparatus according to
Embodiment 1 of the present invention will be described with
reference to the drawings. FIG. 1 is a circuit diagram showing an
air-conditioning apparatus 1 according to Embodiment 1 of the
present invention. The air-conditioning apparatus 1 will be
described with reference to FIG. 1. As shown in FIG. 1, the
air-conditioning apparatus 1 includes an outdoor unit 2 and an
indoor unit 3. The outdoor unit 2 is installed outdoor and has a
compressor 4, a flow path switching unit 9, a first heat exchanger
5, a first cooling unit 30, an outdoor fan 5a, an accumulator 8, a
suction pressure sensor 11, a discharge pressure sensor 12, and a
controller 10. The indoor unit 3 is installed in an indoor space
and has an expansion unit 6, a second heat exchanger 7, and an
indoor fan 7a. The compressor 4, the flow path switching unit 9,
the first heat exchanger 5, the expansion unit 6, the second heat
exchanger 7, the accumulator 8, and the first cooling unit 30 are
connected to each other by a pipe 1b to form a refrigerant circuit
1a through which refrigerant flows.
[0019] The compressor 4 compresses the refrigerant. The flow path
switching unit 9 switches directions in which the refrigerant flows
through the refrigerant circuit 1a. The flow path switching unit 9
switches whether the refrigerant discharged from the compressor 4
flows to the first heat exchanger 5 or the second heat exchanger 7.
With this operation, any of cooling operation or heating operation
is performed. The first heat exchanger 5 allows heat exchange
between outdoor air and the refrigerant, for example. The outdoor
fan 5a sends outdoor air to the first heat exchanger 5. The
expansion unit 6 expands the refrigerant and reduces the pressure
of the refrigerant, and is, for example, an electromagnetic
expansion valve having an adjustable opening degree. The second
heat exchanger 7 allows heat exchange between indoor air and the
refrigerant, for example. The indoor fan 7a sends indoor air to the
second heat exchanger 7. The accumulator 8 stores the refrigerant
in a liquid state. The first cooling unit 30 has a refrigerant flow
path and cools a cooled target.
[0020] The suction pressure sensor 11 is provided at the inflow
side of the accumulator 8 and measures the pressure of the
refrigerant sucked into the compressor 4. The discharge pressure
sensor 12 is provided at the discharge side of the compressor 4 and
measures the pressure of the refrigerant discharged from the
compressor 4. The controller 10 has a microcomputer (not shown)
that controls operation of the air-conditioning apparatus 1, and a
heat-generating element 10a that generates heat such as a power
module. The heat-generating element 10a is, for example, a drive
circuit that drives the compressor 4, and a switching element and
other component included in the drive circuit generate heat. The
controller 10 is housed in an electric component box, for example.
The controller 10 controls operation of the compressor 4 on the
basis of the pressure measured by the suction pressure sensor 11
and the pressure measured by the discharge pressure sensor 12.
[0021] FIG. 2 is a front cross-sectional view showing the outdoor
unit 2 in Embodiment 1 of the present invention, and FIG. 3 is a
top view showing the outdoor unit 2 in Embodiment 1 of the present
invention. As shown in FIG. 2, the air-conditioning apparatus 1
further includes a heat transfer element 20 and a second cooling
unit 40, and both the heat transfer element 20 and the second
cooling unit 40 are provided in the outdoor unit 2. The outdoor
unit 2 has a casing with a quadrangular tube shape, for example. In
the outdoor unit 2, the outdoor fan 5a is provided at an upper
portion, the controller 10 is provided at a lower portion, and the
first heat exchanger 5 is disposed between the outdoor fan 5a and
the controller 10. In addition, as shown in FIG. 3, the first heat
exchanger 5 is mounted on inner walls at four sides of the outdoor
unit 2. As shown in FIG. 2 and FIG. 3, air inlets 2a through which
outdoor air 60 is sucked are formed in the four sides of the
outdoor unit 2, and an air outlet 2b through which the outdoor air
60 is blown out is formed in an uppermost portion. The outdoor air
60 is sucked through the air inlets 2a into the outdoor unit 2 and
subjected to heat exchange with the refrigerant in the first heat
exchanger 5. The outdoor air 60 subjected to heat exchange ascends
and is blown out of the outdoor unit 2 through the air outlet
2b.
[0022] FIG. 4 is a side cross-sectional view showing the outdoor
unit 2 in Embodiment 1 of the present invention. As shown in FIG. 2
and FIG. 4, the heat-generating element 10a of the controller 10 is
connected to a proximal end of the heat transfer element 20, and
the heat transfer element 20 extends upward. The first cooling unit
30 is connected to a first connection portion 22 of the heat
transfer element 20 at a distal end, and the second cooling unit 40
is connected to a second connection portion 23 of the heat transfer
element 20 between the proximal end and the distal end. The pipe 1b
of the refrigerant circuit 1a extends from the first cooling unit
30. The second cooling unit 40 is provided in an air path through
which the outdoor air 60 flows.
[0023] FIG. 5 is a schematic diagram showing the heat transfer
element 20 in Embodiment 1 of the present invention. As shown in
FIG. 5, the heat-generating element 10a is connected to the
proximal end of the heat transfer element 20, the first cooling
unit 30 is connected to the distal end of the heat transfer element
20, and the heat transfer element 20 conveys heat generated by the
heat-generating element 10a. As described above, the
heat-generating element 10a and the heat transfer element 20 are
thermally coupled to each other, and heat is transferred between
the heat-generating element 10a and the heat transfer element 20.
The heat-generating element 10a and the proximal end of the heat
transfer element 20 are connected to each other with a metal plate
21 interposed between the heat-generating element 10a and the
proximal end.
[0024] The second cooling unit 40 is connected between the proximal
end and the distal end of the heat transfer element 20 and cools
the heat transfer element 20. In Embodiment 1, the second cooling
unit 40 is a heat sink having a plurality of fins. As described
above, the second cooling unit 40 is provided in the air path
through which the outdoor air 60 flows. With this configuration,
the heat sink is cooled by the outdoor air 60 flowing through the
air path, and the cooled heat sink cools the heat transfer element
20. Consequently, the heat that is generated by the heat-generating
element 10a and conveyed to the heat transfer element 20 is
rejected to the outdoor air 60. As described above, the second
cooling unit 40 and the heat transfer element 20 are thermally
coupled to each other, and heat is transferred between the second
cooling unit 40 and the heat transfer element 20.
[0025] The first cooling unit 30 is connected to the distal end of
the heat transfer element 20 and cools the heat transfer element 20
using the refrigerant. The first cooling unit 30 is covered with a
heat insulating material 31 that insulates heat of the first
cooling unit 30. With this configuration, the first cooling unit 30
inhibits the refrigerant flowing through the pipe 1b from being
subjected to heat exchange with air. The heat that is generated by
the heat-generating element 10a and conveyed to the heat transfer
element 20 is rejected by the first cooling unit 30 to the
refrigerant flowing through the pipe 1b. As described above, the
first cooling unit 30 and the heat transfer element 20 are
thermally coupled to each other, and heat is transferred between
the first cooling unit 30 and the heat transfer element 20.
[0026] Next, the heat transfer element 20 will be described in
detail. The heat transfer element 20 is a tubular part having a
hollow portion 20a in which a volatile working fluid is sealed,
such as a heat pipe, and the distal end is located above the
proximal end. The heat transfer element 20 is heated at one end and
cooled at the other end so that a cycle is generated in which the
working fluid is evaporated and condensed to transfer heat. In
Embodiment 1, the heat transfer element 20 is heated at the
proximal end, which is located at the lower end, by the
heat-generating element 10a.
[0027] In addition, the heat transfer element 20 is cooled at the
distal end, which is located at the upper end, by the first cooling
unit 30, and is cooled between the proximal end and the distal end
by the second cooling unit 40. With this operation, the heated
working fluid at the proximal end receives heat and evaporates, and
the evaporated working fluid in the gas state ascends toward the
distal end. Then, the working fluid in the gas state ascending
toward the distal end is first cooled and condensed by the second
cooling unit 40. The working fluid condensed into a liquid state
falls toward the proximal end due to gravity. The refrigerant in
the gas state that has not been condensed even by being cooled by
the second cooling unit 40 further ascends and reaches the first
cooling unit 30. Then, the working fluid in the gas state is cooled
and condensed by the first cooling unit 30. The working fluid
condensed into a liquid state falls toward the proximal end due to
gravity. Consequently, heat is transferred in the heat transfer
element 20.
[0028] Next, operation in each operation mode of the
air-conditioning apparatus 1 will be described. First, cooling
operation will be described. In cooling operation, the refrigerant
sucked into the compressor 4 is compressed by the compressor 4 and
discharged in a high-temperature and high-pressure gas state. The
refrigerant discharged in the high-temperature and high-pressure
gas state from the compressor 4 flows through the flow path
switching unit 9 into the first heat exchanger 5 and is subjected
to heat exchange with outdoor air, sent by the outdoor fan 5a, to
become condensed and liquefied in the first heat exchanger 5. The
condensed refrigerant in the liquid state flows into the expansion
unit 6 and is expanded and reduced in pressure into a two-phase
gas-liquid state in the expansion unit 6. Then, the refrigerant in
the two-phase gas-liquid state flows into the second heat exchanger
7 and is subjected to heat exchange with indoor air, sent by the
indoor fan 7a, to become evaporated and gasified in the second heat
exchanger 7. At this time, the indoor air is cooled and cooling is
performed. The evaporated refrigerant in a gas state flows through
the flow path switching unit 9 into the accumulator 8 and then
flows into the first cooling unit 30. At this time, the first
cooling unit 30 cools the heat transfer element 20. Then, the
refrigerant is sucked into the compressor 4.
[0029] Next, heating operation will be described. In heating
operation, the refrigerant sucked into the compressor 4 is
compressed by the compressor 4 and discharged in a high-temperature
and high-pressure gas state. The refrigerant discharged in the
high-temperature and high-pressure gas state from the compressor 4
flows through the flow path switching unit 9 into the second heat
exchanger 7 and is subjected to heat exchange with indoor air, sent
by the indoor fan 7a, to become condensed and liquefied in the
second heat exchanger 7. At this time, the indoor air is heated,
and heating is performed. The condensed refrigerant in a liquid
state flows into the expansion unit 6 and is expanded and reduced
in pressure into a two-phase gas-liquid state in the expansion unit
6. Then, the refrigerant in the two-phase gas-liquid state flows
into the first heat exchanger 5 and is subjected to heat exchange
with outdoor air, sent by the outdoor fan 5a, to become evaporated
and gasified in the first heat exchanger 5. The evaporated
refrigerant in a gas state flows through the flow path switching
unit 9 into the accumulator 8 and then flows into the first cooling
unit 30. At this time, the first cooling unit 30 cools the heat
transfer element 20. Then, the refrigerant is sucked into the
compressor 4.
[0030] FIG. 6 is a schematic diagram showing movement of heat in
the heat transfer element 20 in Embodiment 1 of the present
invention. Next, movement of heat in the heat transfer element 20
will be described. First, the case where an amount of heat
generated from the heat-generating element 10a is small will be
described. As shown in FIG. 6, heat conveyed from the
heat-generating element 10a is absorbed by the working fluid at the
proximal end of the heat transfer element 20 and ascends together
with the evaporated working fluid in the hollow portion 20a of the
heat transfer element 20 (a solid arrow). The heat having ascended
is absorbed by the second cooling unit 40 and rejected to the
interior of the outdoor unit 2. With this operation, the condensed
working fluid falls (a broken arrow), and the heat-generating
element 10a is cooled. The heat having ascended is absorbed by the
second cooling unit 40 and thus does not further ascend in the
hollow portion 20a of the heat transfer element 20.
[0031] FIG. 7 is another schematic diagram showing movement of heat
in the heat transfer element 20 in Embodiment 1 of the present
invention. Next, the case where an amount of heat generated from
the heat-generating element 10a is large will be described. As
shown in FIG. 7, heat conveyed from the heat-generating element 10a
is absorbed by the working fluid at the proximal end of the heat
transfer element 20 and ascends together with the heated and
evaporated working fluid in the hollow portion 20a of the heat
transfer element 20 (a solid arrow). Part of the heat having
ascended is absorbed by the second cooling unit 40 and rejected to
the interior of the outdoor unit 2. At this point, part of the
condensed working fluid falls (a broken arrow). The heat that has
not been absorbed by the second cooling unit 40 further ascends
together with the working fluid in the hollow portion 20a of the
heat transfer element 20 (a solid arrow). Then, the heat is
absorbed by the first cooling unit 30 and rejected to the
refrigerant flowing through the pipe 1b. With this operation, the
condensed working fluid falls (a broken arrow), and the
heat-generating element 10a is cooled.
[0032] According to Embodiment 1, the heat transfer element 20 that
conveys the heat generated by the heat-generating element 10a is
cooled by the second cooling unit 40 earlier than by the first
cooling unit 30 that cools heat using the refrigerant. In the case
where the amount of heat generated from the heat-generating element
10a is small, it is possible to reject heat only with the second
cooling unit 40. On the other hand, in the case where the amount of
heat generated from the heat-generating element 10a is large, the
heat is initially rejected at the second cooling unit 40, and then
rejected at the first cooling unit 30. As described above, the load
on the first cooling unit 30 for cooling the heat-generating
element 10a is reduced. Consequently, for example, the amount of
heat rejected to the refrigerant is smaller than that in an
existing air-conditioning apparatus having only a refrigerant
cooling unit for cooling heat using refrigerant. Thus, for example,
during cooling operation, it is possible to inhibit a reduction in
cooling capacity for cooling an air-conditioned space. As a result,
the air-conditioning apparatus 1 is capable of rejecting heat
generated by the heat-generating element 10a, while inhibiting a
reduction in operating efficiency.
[0033] In addition, the heat transfer element 20 is a tubular part
having the hollow portion 20a in which the working fluid is sealed,
and the distal end is located above the proximal end. In the case
where the amount of heat generated from the heat-generating element
10a is small, the heat conveyed from the heat-generating element
10a is absorbed by the working fluid at the proximal end of the
heat transfer element 20 and ascends together with the evaporated
working fluid in the hollow portion 20a of the heat transfer
element 20. The heat having ascended is absorbed by the second
cooling unit 40 and rejected. As described above, in the case where
the amount of heat generated from the heat-generating element 10a
is small, it is possible to reject heat only with the second
cooling unit 40. In addition, in the case where the amount of heat
generated from the heat-generating element 10a is large, the heat
is initially absorbed by the second cooling unit 40, and the heat
that has not been absorbed by the second cooling unit 40 further
ascends together with the working fluid in the hollow portion 20a
of the heat transfer element 20. Then, the heat is absorbed by the
first cooling unit 30 and rejected to the refrigerant flowing
through the pipe 1b. As described above, the load on the first
cooling unit 30 for cooling the heat-generating element 10a is
reduced.
[0034] In Embodiment 1, the case where the heat transfer element 20
is a heat pipe has been illustrated, but the heat transfer element
20 is not limited to a heat pipe, and may be a metal plate or other
part, for example. The heat transfer element 20 only needs to be
configured in such a manner that heat generated by the
heat-generating element 10a is conveyed in order of the second
cooling unit 40 and the first cooling unit 30. In addition, in
Embodiment 1, the case where the distal end of the heat transfer
element 20 is located above the proximal end has been illustrated,
but the heat transfer element 20 is not limited to the
configuration of the case, and only needs to be configured in such
a manner that heat generated from the heat-generating element 10a
is conveyed to the second cooling unit 40 earlier than to the first
cooling unit 30.
[0035] Moreover, the heat insulating material 31 that is provided
to the first cooling unit 30 and insulates heat of the first
cooling unit 30 is further included. With this configuration, the
first cooling unit 30 inhibits the refrigerant flowing through the
pipe 1b from exchanging heat with air.
[0036] Furthermore, the first cooling unit 30 is provided at the
suction side of the compressor 4. The low-temperature refrigerant
in a gas state flows at the suction side of the compressor 4. With
this configuration, a temperature difference is likely to be
created between the heat transfer element 20 and the refrigerant.
Thus, the cooling capacity of the first cooling unit 30
improves.
[0037] In an existing air-conditioning apparatus that employs a
refrigerant cooling system, the temperature of a heat-generating
element is about 85.degree. C., and the temperature of refrigerant
at the suction side of a compressor is about 10.degree. C. As
described above, a temperature difference of 75.degree. C. is
created between the temperatures of the heat-generating element and
the refrigerant. Thus, when the heat-generating element is to be
cooled by the refrigerant at the suction side of the compressor,
dew condensation may occur in a controller having the
heat-generating element. When dew condensation occurs in the
controller, the dew condensation water may adhere to a charge unit
provided in the controller, causing a problem. In the existing
air-conditioning apparatus, a cooling unit using the refrigerant is
installed at a portion where the relatively-high-temperature
refrigerant in a gas state flows, such as between a condenser and
an expansion unit so that the temperature difference between the
temperatures of the heat-generating element and the refrigerant is
reduced and dew condensation is avoided. However, as the
temperature difference between the temperatures of the
heat-generating element and the refrigerant is small, the heat
rejection performance is inferior, accordingly. In addition, the
necessity to adjust the temperature of the refrigerant arises, and
thus the cost is increased.
[0038] On the other hand, in Embodiment 1, the first cooling unit
30 is away from the heat-generating element 10a. Thus, even when
the first cooling unit 30 is provided at the suction side of the
compressor 4, dew condensation that may be generated by the first
cooling unit 30 does not occur in the controller 10 having the
heat-generating element 10a. Thus, the influence of dew
condensation on the controller 10 is very small, and it is
unnecessary to adjust the temperature of the refrigerant, so that
it is possible to reduce the cost.
[0039] Furthermore, the second cooling unit 40 is described as a
heat sink. With this configuration, heat conveyed to the heat
transfer element 20 is rejected to the air. The second cooling unit
40 may also be a Peltier element that applies a current to a joint
portion of two types of metals and moves heat from one metal to
another metal. As described above, the second cooling unit 40 is
not limited to a heat sink, and only needs to be configured with a
cooling system other than a refrigerant cooling system. In
addition, the second cooling unit 40 may be a combination of a heat
sink and a Peltier element. As described above, as long as the
second cooling unit 40 employs a cooling system other than a
refrigerant cooling system, the number of components may be any
number, and the types of components may be any types.
[0040] The heat-generating element 10a may be a power module for
which SiC is used. With this configuration, the controller 10
having the heat-generating element 10a is capable of operating at
high temperature. Such a heat-generating element 10a is effective
even for the case where the amount of heat generated by the
heat-generating element 10a is large and the amount of heat
rejected to the refrigerant is reduced due to an insufficient
amount of the refrigerant sealed in the pipe 1b.
Embodiment 2
[0041] FIG. 8 is a circuit diagram showing an air-conditioning
apparatus 100 according to Embodiment 2 of the present invention.
Embodiment 2 is different from Embodiment 1 in the position at
which the first cooling unit 30 is provided in the refrigerant
circuit 1a. In Embodiment 2, the same portions as those in
Embodiment 1 are denoted by the same reference signs and the
description of the portions is omitted, and the differences from
Embodiment 1 will be mainly described.
[0042] As shown in FIG. 8, the outdoor unit 2 of the
air-conditioning apparatus 100 has a bypass circuit 101c, a first
refrigerant flow rate adjustment unit 151, a second refrigerant
flow rate adjustment unit 152, and a bypass temperature sensor 113.
The bypass circuit 101c connects the suction side of the compressor
4 and a portion between the first heat exchanger 5 and the
expansion unit 6. The first refrigerant flow rate adjustment unit
151 is provided on the bypass circuit 101c, adjusts the flow rate
of the refrigerant flowing through the bypass circuit 101c, and is,
for example, an electromagnetic expansion valve having an
adjustable opening degree. The second refrigerant flow rate
adjustment unit 152 is provided on the bypass circuit 101c and at
the upstream of the first refrigerant flow rate adjustment unit
151, adjusts the flow rate of the refrigerant flowing through the
bypass circuit 101c, and is, for example, an electromagnetic
expansion valve having an adjustable opening degree.
[0043] The first cooling unit 30 is provided on the bypass circuit
101c and between the first refrigerant flow rate adjustment unit
151 and the second refrigerant flow rate adjustment unit 152. The
bypass temperature sensor 113 is provided on the bypass circuit
101c and between the first cooling unit 30 and the second
refrigerant flow rate adjustment unit 152 and measures the
temperature of the refrigerant flowing through the bypass circuit
101c.
[0044] A controller 110 adjusts the opening degrees of the first
refrigerant flow rate adjustment unit 151 and the second
refrigerant flow rate adjustment unit 152 so that the temperature
measured by the bypass temperature sensor 113 becomes a
predetermined temperature. The predetermined temperature is
between, for example, a bypass temperature upper limit threshold
and a bypass temperature lower limit threshold, and is set to a
temperature, such as a temperature at which dew condensation is
unlikely to occur and a temperature required for cooling the
heat-generating element 10a.
[0045] According to Embodiment 2, the bypass circuit 101c
connecting the suction side of the compressor 4 and the portion
between the first heat exchanger 5 and the expansion unit 6, the
first refrigerant flow rate adjustment unit 151 and the second
refrigerant flow rate adjustment unit 152 provided on the bypass
circuit 101c and each adjusting the flow rate of the refrigerant
flowing through the bypass circuit 101c, and the bypass temperature
sensor 113 measuring the temperature of the refrigerant flowing
through the bypass circuit 101c, are further included, the first
cooling unit 30 is provided between the first refrigerant flow rate
adjustment unit 151 and the second refrigerant flow rate adjustment
unit 152, and the controller 110 adjusts the first refrigerant flow
rate adjustment unit 151 and the second refrigerant flow rate
adjustment unit 152 in such a manner that the temperature measured
by the bypass temperature sensor 113 is between the bypass
temperature upper limit threshold and the bypass temperature lower
limit threshold. With this configuration, even in, unlike
Embodiment 1, the case where it is difficult to provide the first
cooling unit 30 at the suction side of the compressor 4, the same
advantageous effects of Embodiment 1 are achieved.
* * * * *